<template>
    <div class="s-canvas" @click="change()">
        <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
    </div>
</template>
<script>
export default {
    name: "SIdentify",
    props: {
        identifyCode: {
            type: String,
            default: "asdf"
        }
    },
    data() {
        return {
            fontSizeMin: 30,
            fontSizeMax: 40,
            backgroundColorMin: 180,
            backgroundColorMax: 240,
            colorMin: 50,
            colorMax: 160,
            lineColorMin: 40,
            lineColorMax: 180,
            dotColorMin: 0,
            dotColorMax: 255,
            contentWidth: 112,
            contentHeight: 40
        };
    },
    methods: {
        change() {
            this.drawPic();
        },
        // 生成一个随机数
        randomNum(min, max) {
            return Math.floor(Math.random() * (max - min) + min);
        },
        // 生成一个随机的颜色
        randomColor(min, max) {
            let r = this.randomNum(min, max);
            let g = this.randomNum(min, max);
            let b = this.randomNum(min, max);
            return "rgb(" + r + "," + g + "," + b + ")";
        },
        drawPic() {
            let canvas = document.getElementById("s-canvas");
            let ctx = canvas.getContext("2d");
            // ctx.textBaseline = 'bottom'
            // 绘制背景
            ctx.fillStyle = this.randomColor(
                this.backgroundColorMin,
                this.backgroundColorMax
            ); //图形填充颜色设置
            ctx.strokeStyle = this.randomColor(
                this.backgroundColorMin,
                this.backgroundColorMax
            ); //图形轮廓的颜色设置
            ctx.fillRect(0, 0, this.contentWidth, this.contentHeight); //绘制一个填充的矩形 0 0 width height x起点 y起点  宽 高
            ctx.strokeRect(0, 0, this.contentWidth, this.contentHeight); // 绘制一个矩形边框 0 0 width height x起点 y起点  宽 高
            // ctx.clearRect(50,0,this.contentWidth,this.contentHeight)  //清除指定矩形区域，清除部分完全透明
            // 绘制文字
            for (let i = 0; i < this.identifyCode.length; i++) {
                this.drawText(ctx, this.identifyCode[i], i);
            }
            this.drawLine(ctx);
            this.drawDot(ctx);
        },
        drawText(ctx, txt, i) {
            ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax);
            ctx.font =
                this.randomNum(this.fontSizeMin, this.fontSizeMax) +
                "px SimHei"; //字体大小
            ctx.textBaseline = "alphabetic"; //基线对齐
            let x =
                (i + 1) * (this.contentWidth / (this.identifyCode.length + 1));
            let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5);
            var deg = this.randomNum(-45, 45);
            // 修改坐标原点和旋转角度
            ctx.translate(x, y); //移动不同位置  参数偏移量
            ctx.rotate((deg * Math.PI) / 180); //旋转 参数角度
            ctx.fillText(txt, 0, 0);
            // 恢复坐标原点和旋转角度
            ctx.rotate((-deg * Math.PI) / 180);
            ctx.translate(-x, -y);
        },
        drawLine(ctx) {
            // 绘制干扰线
            for (let i = 0; i < 8; i++) {
                ctx.strokeStyle = this.randomColor(
                    this.lineColorMin,
                    this.lineColorMax
                );
                ctx.beginPath(); //新建一条路径
                ctx.moveTo(
                    this.randomNum(0, this.contentWidth),
                    this.randomNum(0, this.contentHeight)
                ); //设置起点x,y
                ctx.lineTo(
                    this.randomNum(0, this.contentWidth),
                    this.randomNum(0, this.contentHeight)
                ); //绘制直线 x,y 一条当前位置到x,y点的直线
                ctx.stroke(); // 通过线条绘制图形轮廓
                // ctx.closePath() //结束闭合路径
            }
        },
        drawDot(ctx) {
            // 绘制干扰点
            for (let i = 0; i < 100; i++) {
                ctx.fillStyle = this.randomColor(0, 255);
                ctx.beginPath();
                // 绘制圆弧或圆，x,y,radius，startAngle,endAngle,anticlockwise // x,y 圆心点，radius 半径，从startAngle开始到endAngle结束
                ctx.arc(
                    this.randomNum(0, this.contentWidth),
                    this.randomNum(0, this.contentHeight),
                    1,
                    0,
                    2 * Math.PI
                );
                ctx.fill(); //通过填充路径的内容区域生成实心的图形。
            }
        }
    },
    watch: {
        identifyCode() {
            this.drawPic();
        }
    },
    mounted() {
        this.drawPic();
    }
};
</script>

